1. Field of the Invention
The present invention relates to a method of recording thumbnail pictures for recorded still pictures onto a recording medium.
2. Description of the Related Art
A disk-type recording medium such as a compact disk (CD) can store high-quality digital audio data permanently, so that it is very popular recording medium. Recently, a digital versatile disk (referred as ‘DVD’ hereinafter) has been developed as a new disk-type recording medium. A DVD can store much larger size than a CD, thus, high-quality moving picture or audio data are recorded on a DVD for much longer time. Therefore, a DVD will be used widely in the near future.
There are three types of a DVD, DVD-ROM for read-only, DVD-R for write-once, and DVD-RAM or DVD-R/W for rewritable. For a rewritable DVD, the standardization of data writing format is in progress.
Recently, a Digital Still Camera (DSC) being capable of storing a taken picture in digital data has been developed. Such a DSC usually has a memory chip of large storage capacity so that it can take high-quality pictures and store audio data associated with the stored pictures as well. In a DSC, the taken pictures are encoded in the format of JPEG, or TIFF while the audio data are done in the format of PCM, u-Law PCM, or IMA-ADPCM.
A DSC has a well-known file system called ‘DCF’ (Design rule for Camera File system) for recording still pictures and audio data. FIG. 1 shows an illustrative DCF. In the structure of DCF, a DCIM (Digital Camera IMages) directory exists under a root directory and many subdirectories may exist under the DCIM. Each subdirectory has 8-digit-long filename that is composed of three numeric digits and five character digits. The three numeric digits should be unique, for instance, one among 100˜999, and the five character digits are arbitrarily chosen by a user. Because the three numeric digits are unique the subdirectories can be created up to 900.
A subdirectory, e.g., subdirectory ‘100ABCDE’ of FIG. 1 can accommodate many data files of which filename is 8-digits long. The filename is composed of four numeric digits and four character digits. While the four character digits are chosen by a user the four numeric digits should be unique among data files if their attributes are different. The data files are still pictures and/or audio files, respectively. The still picture files have extension of ‘JPG’ or ‘TIF’ while the audio files encoded by PCM, u-Law PCM or IMA-ADPCM have extension of ‘WAV’. The filenames of the data files can be same if their extensions are different. Therefore, when a picture file is to be dubbed with audio, a dubbed audio file can be linked with the picture file only if their filenames are made same.
By the way, a digital video recorder (DVR) records video and audio data in a file structure shown in FIG. 2. The file structure of FIG. 2 has a DVR directory under a root directory. The DVR directory includes a menu file ‘menu.tdat’, a mark file ‘mark.tdat’, and their index files ‘menu.tidx’ and ‘mark.tidx’. The menu and the mark file have menu data and mark data respectively and the index files have search data to index menu and mark data in the menu and the mark file.
The ‘DVR’ directory is mandatory for motion picture recording of a DVR. The ‘DVR’ directory has directories ‘PLAYLIST’, ‘CLIPINF’, ‘STREAM’, and ‘STILLINF’. The ‘PLAYLIST’ directory includes playlist files (*.rpls,*.vpls) containing motion-picture and still-picture playitems and title management information. The directory ‘CLIPINF’ includes clip information files (*.clpi) containing information on movie stream management and movie attribute and the directory ‘STREAM’ includes stream files (*.m2ts) containing actual motion-picture data stream packets. The directory ‘STILLINF’ includes still-picture management file (*.stli) containing management information for search and presentation control of the still pictures.
By the way, the aforementioned recording medium of very large capacity is able to store enormous still pictures, so that it is preferable to record thumbnails of recorded still pictures in order to find a desired still picture or a still picture section easily.
Various methods to accept thumbnails of still pictures in the known recording structures is being under discussion among several concerned companies, however, a final method is still pending.